Characterization and applications of negative-index metamaterials
Author
Aydın, Koray
Advisor
Özbay, Ekmel
Date
2008Publisher
Bilkent University
Language
English
Type
ThesisItem Usage Stats
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Abstract
Metamaterials offer novel electromagnetic properties and promising
applications including negative refraction, flat-lenses, superlenses, cloaking
devices. In this thesis, we characterized the negative-index metamaterials that is
composed of periodic arrangements of split-ring resonators (providing negative
permeability) and thin wire (providing negative permittivity) arrays. The
resonances of split-ring resonators (SRR) are investigated experimentally and
theoretically. By combining SRR and wire arrays together, we observed a
transmission band where both permittivity and permeability are simultaneously
negative, indicating a left-handed behavior. Reflection measurements reveal that
the impedance is matched to the free space at a certain frequency range. The lefthanded
metamaterial is also shown to exhibit negative refractive index by using
three different experimental methods namely, refraction from a wedge-shaped
negative-index metamaterial (NIM), beam-shift from a slab-shaped NIM and phase
shift from NIMs with different lengths. Flat-lens behavior is observed from a slabshaped
negative-index metamaterial based microwave lenses. Furthermore, we
demonstrated subwavelength imaging and subwavelength resolution by using thin
superlenses constructed from SRR-wire arrays with an effective negative index.
We have been able to image a point source with a record-level, λ/8 resolution. SRRand wire arrays exhibit negative index provided that the wave propagates parallel
to the plane of SRR structure which makes it hard to fabricate at higher
frequencies. An alternative structure called fishnet metamaterial however could
yield negative index with wave propagation normal to the structure. We observed
left-handed transmission and negative phase velocity in fishnet type metamaterials.
Finally, we studied enhanced transmission from a single subwavelength aperture
by coupling incident electromagnetic wave to a single SRR placed at the near-field
of the aperture.
Keywords
MetamaterialEnhanced Transmission
Subwavelength Resolution
Subwavelength Imaging
Superlens
Flat-lens
Negative-Phase Velocity
Negative Refraction
Negative Permeability
Negative Permittivity
Split Ring Resonator
Left-Handed Material
Permalink
http://hdl.handle.net/11693/14717Collections
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